1. Field of the Invention
This invention relates to an original image storing and reproducing device. More particularly, the invention relates to a light image storing and reproducing device in which an image stored in an information storage medium capable of storing and erasing information repeatedly is reversed or synthesized in the reproducible state.
2. Description of the Prior Art
The information storage medium to be used in this invention comprises an electrochromic material. When an electric current is passed through an electrochromic material, the light absorbing characteristics of the material are changed and as a result a color is developed or the original color is changed. This state can be retained for a long time even after application of the electric current is stopped, and when an electric current of a polarity reverse to that of the primarily applied current is applied to the electrochromic material in such color-developed or color-changed state, the developed color disappears or the color is changed to the original color. This reversible color change depending on the electric polarity is called "electrochromic phenomenon" and a material having such property is called "electrochromic material." In this electrochromic phenomenon, the degree of color development or color change is increased in proportion to the quantity of electricity applied as far as it does not reach a saturation value.
The mechanism causing this electrochromic phenomenon is not simple, but is is construed that in many cases, the electrochromic phenomenon is due to the so-called reduction-oxidation reaction between an electrolyte and a color-developing substance. In this case, the electrolyte and the color-developing substance cannot always be distinguished in the material, and the same substance can be both a color-developing material and an electrolyte in some case. If seen from a different viewpoint, it can be considered that the electrochromic phenomenon is due to the change in light absorbing characteristics caused by injection of electrons into the center of color. It is believed that in effect the electrochromic phenomenon will be caused by combination of these mechanisms.
Since the electrochromic phenomenon is a phenomenon changing electrically the inherent color of a material, a variety of combinations of colors can be considered. Further, whether an electrochromic material permeats light therethrough or reflects or diffuses light does not depend on properties of the electrochromic material per se but it is determined by the method of molding the electrochromic material into an information storage member. Accordingly, when an electrochromic material is used as an indication element, it can be molded into an element of either the transmission type or the reflection type.
In addition to the foregoing structural characteristics and variety, the electrochromic material has a memory property that the developed color can be retained until it is erased by application of electricity of a reverse polarity, and some electrichromic material has such a specific property that the developed color is changed depending on the value of the applied voltage. Because of such variety of characteristics, research works have recently been made extensively on application of electrochromic materials.
A great number of organic and inorganic materials are known to exhibit an electrochromic phenomenon, and all of these materials can be used in this invention. These known electrochromic materials are disclosed in, for example, the specification of British Pat. No. 1,186,541.